Optical Nonlinearity in (EDT-DSDTFVO)2·FeBr4, an Intriguing Molecular Material with Metallic Conductivity, Magnetoresistance Effects, and Quadratic Nonlinear Optical Properties

摘要

The quadratic (∝ E~2) nonlinear optical (NLO) properties of (EDT-DSDTFVO)2-FeBr4 have been investigated: an efficiency equal to 3-6 times that of urea in second-harmonic generation at 1.907 μm has been observed by a powder test, and an effective (d_(eff)) nonlinear optical susceptibility (χ~(2)) tensor component equal to 110 pm/V at 1.064 μm has been determined by confocal μ-SHG in the backscattering geometry. The origin of this effect is ascribable to the presence of strongly interacting EDT-DSDTFVO species organized in non-centrosymmetric stacks in solid state. A computational (ZINDO) investigation carried out on a [(EDT-DSDTFVO)4]~(2+) tetrameric entity at the fractional (p = 0.5) oxidation state leads to a static molecular hyperpolarizability (β_0) equal to 854 x 10~(-30) cm~5 esu~(-1) per tetrameric unit. (EDT-DSDTFVO)2·FeBr4 is the first multifunctional molecular material exhibiting simultaneously conducting, magnetic, and NLO effects. The possibilities of using such absorbent species as micrometer size materials with efficient NLO properties are thoroughly evaluated.